Sandia will join forces early next year with one or more Native American tribes to test a new solar electricity generating system that will be the power source for a water pump. The unit will be placed on Indian lands in the Southwest where it will pump water for agricultural purposes and be close enough to home for observation by researchers in Albuquerque.

DISHING IT UP -- Rich Diver (6216) checks out the first prototype of the 10kW Solar Dish/Stirling Remote Power System, which incorporates the best of advanced solar technology developed at the Labs in recent years. A version of the solar collector will be placed on Indian lands in the Southwest where it will pump water for agricultural purposes. (Photo by Randy Montoya)Download 200dpi JPEG image, 'solar_pix.jpg', 816K

A first prototype of the 10kW Solar Dish/Stirling Remote Power System, which incorporates the best of advanced solar technology developed at the Labs in recent years, consists of 500 square feet of mirror collector panels and an engine that converts solar energy to electricity. The system has operated for more than 500 hours at Sandia's National Solar Thermal Test Facility, meeting all its performance objectives for power, efficiency, and automated operation.

A second-generation prototype planned for this fall will have a water pump attachment. The first solar pumping system to be erected on a reservation is anticipated early in 2001.

"This new solar system is designed to provide power in remote areas for such applications as pumping water, operating a mill, or providing power to an isolated village," says Craig Tyner, Manager of Solar Thermal Technology Dept. 6216. "It will be small enough and, at a price of $30,000 to $40,000, affordable enough to be practical."

He expects the major markets for this system will be international. However, it might also be used in hard-to-reach rural areas in the United States, such as Indian reservations.

Sandia representatives are talking to several Native American tribes in both Arizona and New Mexico about installing demonstration systems on their lands. In the next few months Craig anticipates that a working relationship will be established with one or more Native American partners. Sandia will work closely with the tribes to provide training for operators and maintenance personnel, as well as gain a better understanding of how the system can best serve the people.

The new remote power system is being developed as part of DOE's Concentrating Solar Power Program, which is providing the funding.

Work on the first prototype started about a year-and-a-half ago. The team members from Sandia put together a working system in 10 months -- receiving the go-ahead for the project in October 1998 and producing working hardware by July 1999. Since then they have been refining the system and preparing to erect a new collector and generator with the water pump attachment.

The solar power system consists of three parts. One is the power conversion unit, which features a SOLO 161 Stirling engine, an electric generator, and a solar receiver. The Stirling engine, made by Solo Kleinmotoren of Germany, has a proven track record of hundreds of thousands of hours of operation.

Other parts of the system include the solar concentrator (featuring advanced mirror structures developed at Sandia by Rich and Jim) and system controls (by WG Associates in Dallas), which provide automated (unattended) control, fault detection, data acquisition, and communications.

To generate electricity the sun-tracking mirrors concentrate sunlight onto a receiver that sits on top of a platform extended about 18 feet from the mirrors. The receiver collects and transfers the sun's heat to the engine. The engine is a sealed system filled with helium. As the helium is heated and cooled, its pressure rises and falls. The change in pressure is controlled to make the pistons inside the engine move, producing mechanical power. The mechanical power in turn drives a generator and makes electricity.

One aspect of the new solar system that makes it appealing for electricity production at remote sites is its ability to operate automatically. Without operator intervention or even on-site presence, it starts up each morning at dawn, operates throughout the day, responding to clouds and wind as needed. Finally it shuts itself down at sunset. The system can be monitored and controlled over the Internet.

"It needs very little intervention," Rich says. "It knows where the sun is at all times. It senses sunlight and comes on. And it will automatically shut down if something undesirable happens -- like high winds."

From the ongoing testing, the researchers are already learning about ways to improve the system. They are working on design improvements to reduce structure size and weight, simplify installation, and operate in a stand-alone mode without a grid tie.

Chuck says that over the next several years the technology to build the solar power systems will be transferred to industry partners as suppliers. These suppliers will assume responsibility for planning and implementation of international manufacturing, marketing, sales, and support efforts.

Previous studies by US industry have estimated markets for this type of remote system to be as much as several billion dollars per year -- a great potential for a new system.

For the Sandia researchers working on the project, however, the potential market isn't the only driver for the project.

"The people in the program are really dedicated to making solar power work. They see it as a way to improve the quality of life for people in Third World countries by bringing them clean power. And they think it's a fun project. They had free rein to put their creative skills to work and they're doing amazing things," Craig says.